Conventionally, a so-called cooperative lifting operation of lifting of one cargo with a plurality of cranes is performed. In general, in a cooperative lifting operation, an operator in each crane operates the crane while communicating with each other with a transceiver or the like. However, the operation which is performed while communicating with each other using the voice is inefficient and may cause an accident due to operation errors.
In view of this, for example, PTL 1 discloses an operation control device which achieves a synchronized operation in which the operator in only one of the cranes can control the hook of the other crane to operate along with the hook of the own crane.